This invention is related to an optical-disk playback apparatus capable of selective playback of desired information from an optical-disk on which information is prerecorded. As utilization of optical-disks such as the compact-disc and laser-disk on which video and audio information is recorded have become wide spread recently, demands for higher degrees of usage such as the random access functions are increasing as well as requirements for higher picture and audio qualities. However, instead of complicated conventional search methods using ten-keys and search buttons, a simpler and more convenient search method operable by any operator is considered essential.
As one of such search methods, an interactive video training system with barcode disclosed by U.S. Pat. No. 4,481,412 had been known. In this system, video-disks on which various training materials are recorded are used together with a content table identifying the titles of training material and the workbook carrying barcodes of said titles. This system consists of a barcode reader to read the barcode, video-disk player to play the training material recorded in said video-disk, and a microcontroller to control the video-disk player according to the input from the barcode reader. The operator can indicate the type of desired information to said system by reading the barcode printed in the workbook. The microcontroller interprets the input barcodes and outputs a control signal to the video-disk player to output desired information. The video-disk, upon receiving said control signal, outputs the desired information. By using this system, the operator can retrieve the desired information from said video-disk simply by tracing the printed barcode by a barcode reader.
However, this system includes the following problems. First, since the video-disk operations corresponding to each of the barcodes is determined by the microcontroller incorporated in the system, the types of function attainable by the barcode are set unchangeably at its designing stage. For example, if a barcode was assigned to reproduce a specific section of the video-disk, this barcode can not be assigned to reproduce more than one section of the video-disk if it was desired at a later stage. Furthermore, since the video-disk operation corresponding to each barcode is determined by the microcontroller, the microcontroller designed for use with one video-disk is uncompatible for use with the other video-disks depending on the cases. For example, a video-disk on which numerous training materials recorded in a unit of one minute is incompatible with video-disks on which training materials are prepared in a unit of 30 seconds. Therefore, the barcode must be prepared to have a universal application in order to be able to be used with various types of video-disk and workbooks, and for this, complicated and troublesome operations for retrieving a desired information become essential.
Moreover, if various video-disk functions common throughout these various video-disk systems such as the starting of play, pause, search, etc. are attempted to be standardized in terms of barcode system, one of these function barcodes has to be read first and then the barcodes for the information has to be read in every playback operation, making the operation more complicated. Furthermore, if barcodes compatible with a full range of possible sets of functions corresponding to plural video-disks and workbooks were attempted to be prepared, the numbers of possible functions would be almost infinite, and so the numbers of necessary barcodes also would be impossible to realize. Further, the microcontroller and its software designed for each barcode system has to be replaced every time when the type of video-disks and their associated workbooks are altered, and this is nearly an impossible task to carry out.
In addition, since the conversion of a barcode to a control information signal by a microcontroller is independent of information recorded on a video-disk, difficulties would occur when a correspondence is not established between the barcode and the video-disk. For example, if a video-disk with no correspondence to a barcode were inserted in a video-player to which a wrong instruction read by barcode-reader were given by mistake, an access to a non-recorded section on the disk, or an access to video or audio information undesired by the operator might take place.